1. Field of the Invention
This invention relates to an image sensing apparatus for sensing an image of a subject and recording image data, which represents the image of the subject, on a recording medium. The invention relates further to a method of controlling an operation of this digital camera.
2. Description of the Related Art
An image sensing apparatus is often provided with a liquid crystal display device for displaying the image of a subject in order that the user may check the subject whose image is sensed. Liquid crystal display devices may employ a transmitting-type liquid crystal display panel or a reflecting-type liquid crystal display panel.
A transmitting-type liquid crystal display panel typically has a backlighting device provided on an underside of the liquid crystal display panel. The backlighting device is used to illuminate the liquid crystal display panel from its underside.
In a typical reflecting-type liquid crystal display panel, ambient light strikes a top side of the panel to illuminate the same. Though the reflecting-type liquid crystal display panel makes it possible to conserve electric power, there are occasions where an amount of light sufficient for illuminating the liquid crystal display panel from the top side cannot be obtained when the camera shoots a subject indoors. As a consequence, the image displayed on the liquid crystal device may be difficult to see.
Accordingly, an object of the present invention is to make it possible to conserve power and to facilitate the viewing of an image displayed on a liquid crystal display device even when photography is performed indoors.
According to an embodiment of the present invention, the foregoing object is attained by providing an image sensing apparatus comprising: a shutter-release button; an image sensing device, responsive to pressing of the shutter-release button, for sensing an image of a subject and outputting image data representing the image of the subject; a reflecting/transmitting-type liquid crystal display unit, which includes a backlighting device in which backlighting can be turned on and off, for displaying the image represented by the image data output from the image sensing device; a touch discriminating device for determining whether the shutter-release button has been touched; and a backlight emission controller for turning on the backlighting device in response to a determination by the touch discriminating device that the shutter-release button has been touched.
Another embodiment of the present invention provides a method of controlling the operation of the above-described image sensing apparatus. Specifically, the embodiment provides a method of controlling operation of an image sensing apparatus having a shutter-release button, in which the image of a subject is sensed in response to pressing of the shutter-release button, the method comprising the steps of: providing a reflecting/transmitting-type liquid crystal display unit, which includes a backlighting device in which backlighting can be turned off, for displaying an image represented by image data obtained by sensing the image of the subject; determining whether the shutter-release button has been touched; and turning on the backlighting device in response to a determination that the shutter-release button has been touched.
In accordance with one or more embodiments of the present invention, an image sensing apparatus (a digital camera, a personal digital assistants having a digital camera and so on) is provided with a reflecting/transmitting-type liquid crystal display unit that includes a backlighting device in which backlighting can be turned on and off.
When the shutter-release button is touched by the user, the backlighting device of the reflecting/transmitting-type liquid crystal display unit is turned on. The underside of the liquid crystal display panel constituting the reflecting/transmitting-type liquid crystal display unit is illuminated by the backlighting device. The backlighting device is turned on when the shutter-release button is touched by the user and is not turned on when the shutter-release button is not touched by the user. Since the backlighting device is turned on only when the image of a subject is actually sensed, power can be conserved.
If the shutter-release button is touched when a subject is to be shot, the backlighting of the liquid crystal display panel is turned on. As a result, the image displayed by the liquid crystal display unit is easy to see. In a reflecting/transmitting-type liquid crystal display unit, ambient light strikes the top side of the liquid crystal display panel. The image of the subject displayed by the liquid crystal display unit is easy to see outdoors as well.
The digital camera may further be provided with a shooting-location discriminating device (shooting-location discriminating means) for determining whether shooting is taking place outdoors or indoors. In this case the backlight emission controller turns on the backlighting device in response to a determination by the shooting-location discriminating device that shooting is taking place indoors and, moreover, in response to a determination by the touch discriminating device that the shutter-release button has been touched.
If the shutter-release button is touched when shooting is taking place indoors, the backlighting device is turned on and makes it easy to see the image of the subject displayed by the liquid crystal display unit. When it is determined that shooting is taking place outdoors, the backlighting device will not be turned on regardless of whether or not the shutter-release button is touched. This makes it possible to conserve power. Since a sufficient amount of ambient light strikes the liquid crystal display panel when the digital camera is used outdoors, the image of the subject can be viewed with ease even through the backlighting device is not turned on.
The image sensing apparatus, such as the digital camera, may further be provided with a power-supply voltage sensing circuit, wherein the determination by the touch discriminating device may be made in response to the power-supply voltage sensing circuit sensing that power-supply voltage has fallen below a fixed voltage.
In an instance where the power-supply voltage falls below the fixed level, the backlighting device is turned on when a subject is photographed. This makes it possible to conserve power.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.